docs: Add note for updated terminology (#11802)

# Which Problems Are Solved

For existing customers it could be hard to understand the new aligned
terms we have defined, if they are already used to the "old term"

# How the Problems Are Solved

Adding notes at the top of docs pages to state clearliy new and old
terms.

apps/docs/content/concepts/features/external-user-grant.mdx

@@ -3,6 +3,12 @@ title: External User Role Assignments
 description: "Grant access to projects for external users from other organizations using ZITADEL's external user role assignments"
 ---
 
+<TerminologyUpdate
+    newTerm="Role Assignment"
+    oldTerms={["User Grant", "Authorization"]}
+/>
+
+
 ZITADEL's external user role assignment is a feature that allows you to grant access to projects within your organization to users from other organizations.
 This is useful in scenarios where you want to collaborate with external users without needing them to be part of your organization.
 By using external user role assignments, you can streamline collaboration with external users while maintaining control over access to your projects within ZITADEL.

apps/docs/content/concepts/structure/administrators.mdx

@@ -6,6 +6,12 @@ sidebar_label: Administrators
 
 import AdministratorDescription from "./_administrator_description.mdx";
 
+<TerminologyUpdate
+    newTerm="Administrators"
+    oldTerms={["Members", "Memberships", "Managers"]}
+/>
+
+
 <AdministratorDescription components={props.components}  name="AdministratorDescription" />
 
 Notes:

apps/docs/content/concepts/structure/instance.mdx

@@ -4,6 +4,11 @@ description: "Overview of ZITADEL Instances—the virtual tenants providing full
 sidebar_label: Instances
 ---
 
+<TerminologyUpdate
+    newTerm="Instance"
+    oldTerms={["IAM"]}
+/>
+
 ## Instance Structure
 
 An instance is the top node in ZITADEL's data hierarchy.